How many friends does one person need? Are online social networks such as Facebook helping to expand our friendship networks? Can we make lasting relationships only online?

These are some of the questions explored and debated by Robin Dunbar, Professor of Evolutionary Theory at Oxford University, in a discussion chaired by Roy Cross, on the subject of Dunbar’s book, How Many Friends Does One Person Need? The theory of “Dunbar’s Number”, formed in the 1990’s, argues that humans can only manage meaningful relationships with a maximum of 150 people, since their brains are not equipped to manage more – this came about through Dunbar’s research into primates and how they operate in large social groups.

Dunbar provides interesting examples to support his theory – the number ‘150’ occurs across society and business: from the Domesday book, describing the average size of an English village, to settlers in Hutterite (similar to Amish) communities, and even in the Goretex company factories, where each new factory is built for a maximum of 150 people in order for successful business function and for people to still be able to know each other.

There are several references to academic studies, from how teenagers maintain relationships after moving away from home (which finds that family relationships are much more resilient than friendships – friendships are fragile and require maintenance) to experiments into notions of kinship and ‘belonging’, tested in email surveys. This “sense of belonging” still emerges as being tremendously important in today’s relationships, even online.

Dunbar’s interest also lies in how technology prevents a relationship from declining, with the findings showing dramatic differences between men and women. The audience hoots with laughter in response to the findings that on average, when speaking on the phone, men spend seven seconds and women spend thirty minutes – leading to the somewhat predictable conclusion that men focus on action and women on communication.

The question and answer session is stimulating: what does Dunbar think about relationships which have been created online? He insists that there are lots of reasons why we need to get up close and personal – we can’t kiss online, and on the Internet, you can’t read a person’s face when you tell them you love them. What degree of overlap is there in a person’s 150 friends? Dunbar responds that the first layer of five friends is densely connected. However, modern economic mobility means that wherever we go for work or study, we create pockets of friends throughout the world and our network becomes fragmented and geographically distributed. The author’s response to the question about the absence of references to academic studies in the book is disappointing for some readers: apparently the book ended up being longer than originally intended, preventing their inclusion.

Dunbar closes what has been a thought-provoking session by reinforcing the idea that human beings need to work harder at creating a sense of belonging and social cohesion. In the author’s opinion, whilst technology is good at “holding up the relationship” in friendships, face to face interaction is still fundamental, or relationships will die. As for the theory of “Dunbar’s Number”, the debate continues on Facebook and several social media blogs. As people continue to play out their lives more and more online, it’s an argument that shows no sign of abating.